Coach Jim Harbaugh said tight end Vernon Davis is day-to-day with a hamstring injury that he suffered late in the loss at Seattle on Sunday. Davis tweeted that physicians instructed him to rest this week, but he expects to play Sunday against the Colts and his younger brother, cornerback Vontae Davis. It will be the first time the brothers face each other since Vontae Davis entered the NFL in 2009.

Harbaugh said safety Eric Reid continues to have no symptoms of a concussion. Reid left Sunday's game with a possible concussion in the first half. The rookie, who has been outstanding so far this season, will have to pass a league-mandated concussion test before returning.

Harbaugh said the team did not sign a backup nose tackle -- starter Ian Williams was lost for the season with a broken ankle at Seattle, and Glenn Dorsey will take over -- because of the good work of Tony Jerod-Eddie. Harbaugh said Jerod-Eddie is ready to take the next step and the team “feels good” about it.

Harbaugh said newly signed Owen Marecic will back up Bruce Miller at fullback and play on special teams. Marecic was a favorite of Harbaugh’s at Stanford.

Quarterback Colin Kaepernick on the season-ending injury to his friend Williams: “It’s tragic.”

Harbaugh said he heard there is a “crew” of former Stanford players who will be at the Colts-49ers game Sunday. The Colts, of course, are quarterbacked by Andrew Luck, who starred under Harbaugh at The Farm.